1. Field of the Invention
The present invention relates to an image recording apparatus which records an image on both sides of a recording medium by turning over the recording medium, and particularly to an apparatus for turning over a recording medium.
2. Description of Related Art
There has been proposed an image recording apparatus that can record an image on both sides of a recording sheet, as disclosed in JP-A-11-209008, for instance. Such an image recording apparatus includes a sheet supply tray and a feed path. The sheet supply tray accommodates a recording sheet, and a recording portion is disposed in the feed path. The recording sheet is supplied from the sheet supply tray and fed along the feed path, during which the recording portion records an image on one (which may be referred to as a “first surface”) of two opposite sides or surfaces of the recording sheet. Thereafter, the recording sheet is fed backward into a switch-back path by being nipped between a switchback roller pair. Via the switch-back path, the recording sheet is again fed to an upstream portion of the feed path, while being turned over. The upstream portion is a portion of the feed path located upstream of the recording portion. The recording portion records an image on the other side (which may be referred to as a “second surface” or “reverse side”) of the recording sheet that has been turned over. The recording sheet is then ejected out of the image recording apparatus.
When the recording sheet is fed backward into the switch-back path by being nipped between the switchback roller pair, there is a possibility that friction resistance between the recording sheet and an inner wall surface of the switch-back path causes bending of an end portion of the recording sheet on the front or leading side in a feeding direction of the recording sheet.
In particular, where the recording portion is of inkjet type, ink droplets forming the image on the surface of the recording sheet are not evenly landed or distributed with respect to a width direction of the recording sheet, i.e., a direction perpendicular to the feeding direction, resulting in a variation in a rigidity and a friction coefficient of the recording sheet with respect to the width direction of the recording sheet. This widthwise variation in the rigidity and friction coefficient leads to an unevenness with respect to the width direction in an amount of bending of the recording sheet. Therefore, even when the recording sheet is not skewed at a portion thereof nipped between the switchback roller pair, the end portion of the recording sheet on the leading side may be disadvantageously skewed. Where the recording portion is not of inkjet type, the possibility of occurrence of such a skew is relatively low as compared to the case of inkjet type, but not completely free from the possibility thereof.